High frequency circuits



June 29, 1937. F. A. KOLSTER HIGH FREQUENCY CIRCUITS Filed Oct. 12, 1932 FIG. 2

FIG. 6

INVENTOR FREDERICK A. KOLSTER BY EZ'W ATTORNEY Patented June '29 1937- PATENT 'jOFFiCE mcn FREQUENCY cmcm'rs Frederick A. Kolster, Neuron, N. 12', amnion-b Federal'Telen-aph OompaimN corporation ofcalifornia ewar k, .N. 8.. a

Application cam: i2, 1932, Serial macs-1.864 'ja Claims. (Oust-4o This" invention relates to high frequency eir cuits, and particularly .to circuitsfor use in connection with vacuum tubes designed-to operate in the high frequency region of the radio spectrum.

. An object of the invention is to provide a device for use in a high frequency oscillator circuit which will increasethe frequency stability ofthe circuit.

device which may be used in connection with any high frequency circuit, such as an amplifier circult or oscillating circuit, for example, to improve,

'- the operating characteristics. of the circuit.

'15 A tunedcircuit will resonate to a frequency dependent upon the value of the inductance, ca-

pa city and resistance in the circuit. with an Y increase in either inductance or capacity, the.

resonance point of the circuit will be changed to go alower frequency, and vice versa. In order to provide a circuit which may be tuned at a very .high frequency, it is, therefore, necessary to make; the values of inductance and capacity correspondingly small. I

In connectionwith oscillators] a .tan'k circuit is frequently employed. Such a circuit may be roughly defined as a resonant circuit in which the ratio of capacity to inductancejis'relatively large. ..'I'he circuit then has, a flywheel effect,

[ that is,-it has large circulating currents which tend to stabilize the frequency of the oscillator.

To obtain the maximum benefit from such a cir-' cult it is important to gnake the resistance .of the circuit as low-as possible as this increases the 5 sharpness of resonance andpermits larger air-- culating currents to flow.

A feature ofthis invention" is the particular shape and construction of a device which may be used as a tank ciicuit for high frequencies, and which will have a particularly hi h capacity relative to its inductance for the frequency at which it is resonant, and have a particularly low value of resistance at this frequency.

In the drawing; i 5 Fig. 1 is anend view of one species oithe invention;

Fig. 2 is a side view-of the device shown in Fig. l; I

Fig- 3 is a side view of another species of the invention; and I Figs. 4, 5 and 6 are phantom views of additional species of the invention. In Figs. 1 and 2, a metallic tube-i has mounted thereon .two metallic caps L and 3 having ex- '55 tended rims d. The entire structure may be of Another object .of the'invention is to provide a able.

copp r. for example. One or both of the caps may be adjustable so that the distance between rims lmay be varied. for tuning. When such a device is used as a resonant or tank circuit in high frequency circuits such as that of an oscillator, the tube acts as an inductance while a capacity" is formed between 'the'rims l. The in-v ductauce of the tube l is very low while the capacity between the rims l is relatively very high. There is apparently very little inductance in the circuit outside of that of the tube l. The tube i and the caps-have, of course, an extremely low value of resistance so that all of the conditions named above for a tank circuit are met.

,A device such as that. shown in Figs. 1 and'2, as well .as the devices shown in any of the other figures, may be usedin a circuit such as that shown in United States Fatent N0. 1,828,706 18- sued' October 20, 1931, to Geoffrey G. Kruesi and me. In the circuitsishown in that patent, this device could be used to replace the resonant circuits l'i. Leads to the device could be connected,

for example, to adjacent points on opposing rims 4, or to the ends oftube I.

,connect the leads across only a portion of the II it is desired to inductance of the tank circuit, holes, as i2, i3, Fig. 2, may be made through the caps 2 and 3, and the leads run through these holes and connected to the tube I. These leads need not interfere with the adjustment of the caps 2 and 3 as th holes may be large enough to allow'for any desired adjustment. Similar holes may be made in the devices shown in the other figures. In Fig. 3'they may be made in the cap l4, and in Figs. 4, 5 and 6 in the outer cylinder.

The devices shown in Figs. 3, 4 and 6 operate in the'same manner as that shown in Figs. 1 and 2 In each case there is a tube 1 which supplies the inductance, and a pair of' plates 4 which supply the capacity. In each case'the capacity is vari- In Fig. 3 it is variedby moving the tube 5 axially. InFig. 4 the tubel is in two sections and one of the plates 4 is attached to each section. The capacity may be'varied by moving the upper section of tube I axially, or this section of the tube may be threaded in a bushing 6 and the :capacity varied byerotating knob 5. In Fig. 6 one of the plates 6 is secured to an inner shaft i and the capacitymay bevaried by moving this shaft axially, or the shaft may be threaded in a bushing 8 and thecapacity varied by rotating knob 9.

In Fig. '5 a. tube to may be moved relatively to another-tube ii of larger diameter, so that .the tube is slides inside the tube ii. The capacvided in the case of any of the devices shown,

in order to increase the capacity. In Figs. 2, 3, 4 and 6, for example, the rims or plates 4 may be made larger. 'In Fig. 5 additional concentric tubes might be provided at each end of the structure and these tubes might be interleaved to increase the capacity, and in Figs. 2, 3, 4 and 6- additional interleaving plates might be provided ior the condenser shown.

The structure shown in all the figures is selfshielded. The devices of Figs. 4, 5 and 6 may be evacuated or put under pressure; as circum'-- .stances and operating characteristics indicate to be desirable.

A special advantage may be obtained with the device shown in Fig. 3 by mounting an electronic tube'coaxially with tube I with'its base adjacent the right-hand plated. A number of parallel leads from the plate of the electronic tube may then'be'run' throughholes in the righthand plate t and connected tothe'inner plate 5. A lead from the grid may then be connected to the center of right-hand plate 3. The inductance formed by the plate and grid of the electronic tube will then be reduced to a minimum.

What is claimed is:

1. An electrical circuit comprising, as a composite unit, a. metallic cylinder forming an inductance element of the circuit, and a'pair of dome-shaped metallic devices mounted at opposite, ends of said cylinder in electrical contact therewith and having surfaces extending towards one another, said surfaces having adjacent rims in spaced relation to form a capacity element of said cii'cuit.-

2. An electrical circuit comprising, as a composite unit, a metallic cylinder forming an inductance element, a pair of annular metallicplates adjacent to one another, surrounding said cylinder and forming a capacity element of said circuit, and a pair of conducting elements mounted on said cylinder and supporting said plates in spaced relation and having surfaces of low resistance electrically connecting the ends of said cylinder to said plates.

3. An electrical device comprising, as a com--- posite unit, a conductive plate forming one electrode of a condenser, a. conductive tube forming an inductance element of an electrical circuit and having said conductive plate mounted thereon at one end thereof .in electrical contact there-. with a conductive cap mounted on said tube in adjustable .spacedrelation to said plate and sur rounding said tube in electrical contact therewith and a' conductive plate carried by said'cap and positioned opposite and in spaced relation to said first mentioned plate and forming the other -elec trode of said condenser which cooperates with saidinductance element to provide a closed oscillatory circuit.

.4. The combination-of an electrically conductive cylinder, an electrically conductive tube electrically connected to'one end of thedcylinder and extending .thereinto, a conductive plate at the inner end of said tube in electrical contact therewith, a second electrically conductive tube adjustably mounted at the other end of said cylinder in electrical contact therewith and extending thereinto, and a second conductive plate "at" heinner end. of said second tube and co-operating with the other said" plate totorm a condenser, said cylinder andsaid tubes constituting upon said tubular element, and means for connecting leads across a portion only of said inductance element, said. tubular metallic. members having openings therein for the passage of said 15 leads. M

6. An electrical circuit comprising, as a composite unit, a tubular inductance element, a capacity element comprising a pair of relatively movable spaced plates, and metallic members of 20 substantially no resistance surrounding said 'tu bular elements in engagement therewith and supportedthereby and physically supporting said plates in said spaced relation whilst electrically 7 connecting said elements in a closed oscillatory circuit.

7. An electrical 'circuit'comprising, as a composite unit, a hollow conducting member forming an inductance element of said circuit, two conducting plates, and'means comprising two '30 members mounted in adj'ustable spaced relation on said conducting element and physically supporting said plates upon said conducting element with one plate adjacent but spaced from the other to form a Q pacity element of the circuityand electrically connecting said inductance and said capacity elements in series to form a closed .oscillatory circuit. I a 8. An electrical device comprising, as a composite unit, a conducting 'rod constituting an in rod and electrically connected to and physically supported by said rod at spaced points thereon;

said pair of members forming a capacity element for cooperating with said inductance element to provide a closed oscillatory circuit.

9. A high frequency circuit comprising, as'a composite unit, a conductive supporting rod, two

conductive elements mounted in adjustable spaced relation upon and supported by said conductive supporting rod, plates carried by said elements and constituting the condenser electrodes and said conductive supporting rod constituting the inductance ofthecircuit, andsaid conductive elements surrounding and forming a shield for said conductive supporting rod.

10. An electrical device, according to claim 8, characterized in this, that one of said conductive members is a flat annular plate forming the rim of a dome-shaped metallic member having an opening in the top thereof through which said conducting supporting rod extends.

, 11."An electrical device, according to claim 8, wherein each of ,said capacity element members is formed by the rim of a dome-shaped metallic member in which holes are provided for thepassage. of connecting leads to said inductance element.

12. An electrical circuit'comprising, as a coma tubular member encircling said rod and phys- 7 ically supported thereby and thereon, said tui bular member supporting one of said plates intermediate the ends of said rod and electrically connecting it to said inductance element, and means electrically c nnecting the other of said plates to .saidinducta ge element and serving mechanically to support said other plate thereon with the space therebetween being intermediate the ends of'said rod and the distance between the plates being adjustable by movement of the tubular member lengthwise of said rod whilst maintainingelectrical contact therebetween.

v 13. An electrical circuit comprising, as a composite unit, a pair of conducting annular plates in spaced relation forming a capacity element of the circuit, a tubular member carrying at one end thereof one of said plates, means constituting an inductance element of the circuit and comprising a conducting rod passing through and physically supporting said tubular member by telescopic engagement therewith, and means for supporting the other oflsaid annular plates on said rod in concentric relation thereto and in spaced relation to the said one plate.

14. A high frequency circuit comprising, as av composite unit, a pair of fiat annular metallic members forming the electrodes of a capacityelement of the circuit, a metallic rod concentrically disposed within said annular members and forming an inductance element of the circuit, a conducting tubular member surrounding said rod and'at one end adjustably engaging said rod so as to be supported thereby and thereon and carrying one of said annular members at the other end thereof, and means for supporting the other annular member on said rod in spaced parallel relation to said one annular metallic member. g

15. An electrical circuit comprising, as a composite unit, a hollow conducting element forming an inductance in said circuit, two conductingplates, and metallic members in encircling engagement with said element and physically supporting said plates upon said conducting element l with one plate adjacent the other to form a capacity-element of the circuit, and electrically connecting said inductance and said capacity elements in s ries to form a closed oscillatory circuit.

16. A high frequency circuit comprising, as a composite unit, a conductive supporting rod, two

' tubular conducting elements mounted in spaced relation uponand supported by said conductive supporting rod, said elements being provided with adjacently positioned surfaces constituting the capacity of said circuit and said conductive supporting rod constituting the inductance. of the circuit, and said conductive elements forming a shield for saidconductive supporting rod.

17. An electrical device comprising as a composite unit, a conductive plate forming'one elec- 'trode of a condenser, a conductive tube forming an inductance element of an electrical circuit and having said conductive plate mounted thereon'at one end thereof in electrical contact therewith,'a

dome shaped metallic member mounted. on said tube in electrical contact therewith and in adjustable spaced relation to said plate, and a'con-" ductive rim for said member positioned opposite,

and in spaced relation to said plate and forming the other electrode of said condenser which cooperates with said inductance element to provide a closed oscillatory circuit, the said adjustable spacing being efiected by a movement of said member lengthwise of said tube.

18. An electrical circuit comprising, as a composite unit, a metallic rod forming an inductance element of the circuit, a pair of dome shaped metallic devices mounted in spaced relation on said rod in, electrical contact therewith, and a plate carried by each device, said plates being positioned in opposing spaced relation to form electrodes of a capacity element of said circuit, and one of said devices being movable on said rod so as to ,vary the spacing of said plates, theme by to change the capacity of said capacity element.

19. An electrical circuit comprising, as a composite unit, a cylindrically shaped metallic member constituting an inductance element of said circuit, two metallic plates constituting the electrodes of a capacity element of said circuit, means mounted on said member at one end thereof supporting one of said plates and electrically connecting it to said member, and means adjustabl-y mounted on said member'at the other end thereof supporting the other of said plates in spaced relation to the-said one plate and electrically connecting it to said member, whereby the spacing of said platesmay be adjusted to vary the capacity of said capacity element.

- 20. An electrical circuit comprising a cylindrically shaped metallic member constituting an inductance element of said'circuit, two metallic plates positioned intermediate the ends of said member and constituting the electrodes of a capacity element of said circuit, means mounted said capacity element whilst maintaining said capacity element within the length of said member.

21. An electrical circuit comprising a cylindrically shaped metallic member constituting an inductance element of said circuit, two metallic plates constituting the electrodes of a capacity element of said circuit, means mounted on said member at one end thereof supporting one of said plates and electrically connecting it to said member, and means mounted on said member at the other end thereof in adjustable spaced relation to the said first mentioned means and supporting the other of said plates in adjustable spaced relationto the said one plate and electrically connecting it to said member whereby the space between said plates may be varied by movement of the second mentioned means along the length of said member to adjust the capacity of said capacity element.

mnamcx 'A. Kons'rER. 

